(1) Field of the Invention
The present invention is directed to valve seals, more specifically to resilient seals for rotatable-type valves.
(2) Description of the Related Art
Rotatable-type valves are well known and are found in infinite variety. This variety is evidenced by their wide use in commerce in a multitude of applications. This type of valve is most often used in fluid piping to start and stop the flow of fluid through the piping by opening and closing the valve. The specific construction of such valves differs widely depending on the application in which they are used. Generally, however, a valve of the type involved in the present invention includes a valve housing with a center bore defining a flow passage and a hub located substantially near the middle of the length of the valve housing. The valve housing generally has at each end an orifice defined by the flow passage, although there may be more if a specific application so requires. One of the orifices is an inlet port and the other is an exit port. Usually, these ports have a common axis and are positioned 180.degree. apart along the through axis of the flow passage.
A rotatable valve element, for example a disk valve, is pivotally disposed within the flow passage and is rotatable about an axis perpendicular to the through axis of the flow passage between an open position, in which it is generally parallel to the through axis of the valve housing, and a closed position in which it is generally perpendicular to the valve housing through axis. The rotatable valve element is mounted to a shaft, itself rotatably mounted to the valve housing at the hub with bushings or bearings. As is well known in the art, the shaft may be connected to a mechanical drive mechanism or operated manually to rotate the shaft and thereby rotate the valve element within the valve body between the open and closed positions.
The valve body has, on the interior surface of the flow passage, an internal annular groove adapted to receive and retain a seal. The internal annular groove is located so that at least a portion of the seal retained therein lies in the plane of the valve element, perpendicular to the through axis of the flow passage and located so that it will engage with the valve element in a leak-tight engagement when the valve element is rotated to its closed position. The seal may be, as is well known in the art, retained in the retaining groove by many means, including adhesives, frictional engagement, welding, and riveting.
Various types of seals have been proposed and used to seal rotatable-type disc valves. The seals of the prior art, however, at times fail to effectively seal under high pressures, do not effectively seal bi-directionally, or are unable to self adjust to increases in liquid pressure.
Thus there is a need for a valve seal that can utilize increasing pressure to more effectively seal the valve. Further in certain applications it is often desirable, if not critical, to employ rotatable-type valves in applications where liquid pressure may, at different times, flow from either direction into the flow passage. Thus, there is a need for an effective bi-directional valve seal. Still further, in many applications, in addition to the need for bi-directional sealing, it is desirable to use a seal that can effectively seal as the sealed liquid pressure increases without operator adjustment. Thus there is a need for a seal that is capable of self adjusting to increased liquid pressure to continue to effectively seal once the valve element is in the closed position.